In March 2021, Guangzhou Shipyard International Co., Ltd. (GSI) signed a construction contract for this type of ship with Mediterranean Shipping Company (MSC), planning to build 8 vessels. Before that, shipbuilding enterprises in South China, including GSI, had never built ultra-large container ships with such a large tonnage. After undertaking this batch of ship orders, GSI successively overcame technical problems such as the cutting and welding of crack arrest steel, and the automatic welding of crack arrest steel by robots.

During the transportation process of large container ships, they need to bear the huge weight of containers. Under the action of ocean waves, they are extremely prone to torsion and cracking. In order to ensure the strength of the hull, it is necessary to use crack arrest steel with large thickness, high strength, and extremely strong low-temperature toughness, strain capacity and anti-cracking performance at the positions where the whole ship is most stressed and subjected to alternating load strength, such as the deck and the hatch coaming. This can effectively guarantee the anti-cracking performance and structural stability of large container ships.

The maximum thickness of crack arrest steel can reach 85 millimeters. How to ensure the cutting and welding quality and efficiency during the cutting and welding process is a key technical problem that must be solved in the construction of ultra-large container ships. At the beginning of undertaking this project, the large container ship project team of GSI, in conjunction with the Manufacturing Department, the Planning and Construction Support Department and the Construction Method Research Institute, formed a crack arrest steel research and development team, and successfully overcame the technical problems of cutting and welding of large-thickness crack arrest steel.